Many cardiac treating agents have been known as useful in the treatment of cardiac insufficiency. In particular, as the 4-acetyl isoquinolinone compounds, 4-acetyl-1-methyl-7-pyridyl-5,6,7,8-tetrahydro-3(2H)-isoquinolinone and the like have a high activity, as shown in Japanese Patent Application No. 144008/1985, and are useful cardiotonics having a wide safety range.
Conventionally, these 4-acetyl isoquinolinone compounds have been prepared by condensing 2-acetyl-4-pyridyl cyclohexanone with cyanoacetamide to produce 4-cyano-1-methyl-7-pyridyl-5,6,7,8-tetrahydro-3(2H)-isoquinolinone and then reacting the obtained compound with a Grignard reagent such as methyl magnesium iodide and the like followed by decomposition by an acid.
However, this conventional process is uneconomical as it requires many steps, and thus an economical process having shorter steps has been desired.